The invention relates to a closure fault indicator for locking means interposed between two elements able to occupy with respect to one another an open position and a closed position.
Such an indicator can in particular be used on an aircraft engine for immediately informing ground personnel of a closure fault or shortcoming of locking means interposed between the pod cowls of said engine.
Aircraft engine pods are normally equipped with cowls, whose opening gives access, when the aircraft is on the ground, to various equipments, systems, etc. for maintaining the same. When the aircraft is in flight, the cowls are closed and have a shape such that they ensure the aerodynamic continuity of the complete engine.
More specifically, the pod of a ducted turbofan engine is generally equipped with at least one pair of cowls, respectively to the right and left, which are placed around the engine fan. Each of the cowls has an approximately C-shaped cross-section in a transverse plane perpendicular to the longitudinal axis of the engine. A hinge makes it possible to articulate the upper edge of each of the cowls on the upper part of the engine. As a result of this arrangement it is possible to obtain access to various equipments of the engine, particularly for maintaining the same, by raising the cowls.
The lower edges of the cowls are also equipped with locking mechanisms for locking the cowls in their closed position when said mechanisms are actuated. Said locking mechanisms generally comprise a male part and a female part mounted on the respective lower edges of the cowls, so as to be cooperate with one another when the cowls are closed.
U.S. Pat. No. 4,531,769 relates to an improved locking mechanism for ensuring the closure of two cowls surrounding an aircraft engine. This knuckle joint-type mechanism comprises a main hook articulated on the lower edge of a first cowl, so as to be able to penetrate a complimentary opening linked with the other cowl. The position of the main hook is secured by the use of a second hook. The locking of the mechanism is controlled by depressing a handle.
When such a locking mechanism is installed on an aircraft engine, the situation may arise where the operator responsible for closing the cowls forgets to carry out locking or does not perform this operation in a satisfactory manner. Thus, when a locking mechanism like that described in U.S. Pat. No. 4,531,769 is used, it is possible to actuate the handle in the closing direction when the hook is not engaged in the complimentary opening linked with the other cowl. In this case, as in the hypothesis where the operator forgets to manipulate the locking mechanisms after lowering the cowls, it is virtually impossible to see that locking has not taken place or has not been performed in a satisfactory manner. Thus, as a result of their considerable weight, the cowls automatically arrive in position by gravity and their lower edges do not project beyond the air intake. Moreover, existing locking mechanisms do not have really projecting portions making it possible to indicate to the operator that there is a closure defect.
In EP-A-596 070 said problem is solved by mounting on the lower edge of one of the two cowls a pivoting or sliding arm, which visibly hangs beneath the engine when the two cowls are lowered, but not locked. The indication of a closure fault can be further improved by adding a flag to the end of the pivoting or sliding arm.
According to EP-A-596 070, the cowls can only be locked after the operator has manually raised the arm in order to house it on a receptacle provided for this purpose. When locking takes place, a pin linked with the opposite cowl penetrates the arm in order to maintain it in its retracted position. When the cowls are unlocked, a spring automatically brings the arm into its projecting position, which is visible from the outside.
The presence of such an indicator beneath the cowls equipping an aircraft engine prevents a defective or non-existent actuation of the locking mechanisms. However, this indicator suffers from a certain number of disadvantages.
Firstly, in the most frequent case where the engine is installed beneath the aircraft wing, the cowl locking mechanism is positioned below the engine, at a point very close to t he ground and therefore difficult of access. When the operator opens or closes the cowls, he has to crouch in order to manipulate the locking mechanisms. The arm added to the locking mechanism according to EP-A-596 070 then constitutes a projecting part, which is added to other contusive parts of the engine and may injure the operator.
Moreover, when the cowls are closed again, the indicator described in EP-A-596 070 makes it necessary for the operator to raise the arm whilst locking the cowls. This operation is particularly irksome and difficult to perform in the position which he occupies.
In addition, the indicator described in EP-A-596 070 significantly complicates the existing locking mechanisms, because it requires the addition of two separate parts to the two cowls, as well as an alignment between the pin ensuring the locking of the arm in the retracted position and the hole formed in the arm for receiving said pin. This operation can prove irksome, bearing in mind the wear and clearance assumed by the parts when in use.
The invention relates to a closure fault indicator making such a fault clearly visible and whilst obviating the disadvantages of the indicator described in EP-A-596 070, i.e. in particular by not complicating either manufacture or use of the locking mechanism.
According to the invention, this result is obtained by means of a closure fault indicator for locking means interposed between two elements able to occupy with respect to one another an open position and a closed position, said indicator being characterized in that it comprises retractable abutment means able to automatically maintain the two elements spaced from one another during a passage from the open position into the closed position.
Advantageously, the indicator is arranged in such a way that the locking means can only be closed when the abutment means are retracted.
Moreover, said arrangement is preferably such that the abutment means can only be retracted by a deliberate action on the part of an operator. This deliberate action can be carried out by using a suitable tool.
According to a preferred embodiment of the invention, the retractable abutment means comprise at least one abutment member displaceable between a stable position in which the mobile element automatically bears against the abutment member when it moves from its open position into its closed position, and an unstable state in which the mobile element can move into its closed position.
Advantageously, elastic means then urge the abutment member towards its stable state.
The abutment member can in particular be fitted so as to be able to pivot about a fixed axis, in order to move from its stable state into its unstable state and vice versa.
In the particular case where the two elements are mobile, the retractable abutment means comprise two abutment members, each of which is allocated to one of the elements.
The two abutment members can then be installed so as to be able to pivot about the same fixed axis.
According to a preferred application of the invention, the two elements are pod cowls of an aircraft engine.
In this case, the borders or edges of the cowls, which can be retracted when said cowls are in the closed position and which are visible when they are kept spaced by retractable abutment means, incorporate means able to increase the visibility thereof, such as fluorescent paint or a bright colour.